Function WriteFile

internal/tools/write.go:12–32

WriteFile writes content to path, creating parent dirs. Errors return as part of the output string (bash convention), never as a Go error, so the model sees a write failure the way it sees a non-zero bash exit.

(path, content string)

// appends instead of overwriting, which is how a file too large for one
// streamed tool call gets built: first part plain, every later part appended.
// Errors return as part of the output string (bash convention), never as a Go
// error, so the model sees a write failure the way it sees a non-zero bash exit.
func WriteFile(path, content string, appendMode bool) string {
	if path == "" {
		return "(empty path)"
	}
	// Refuse an existing non-regular target: open(2) with O_WRONLY on a FIFO
	// with no reader blocks forever, leaking the tool goroutine past Ctrl+C
	// (which cancels the turn but can't unblock the open). Stat never blocks;
	// directories fall through to os.WriteFile's immediate EISDIR.
	if info, err := os.Stat(path); err == nil && !info.Mode().IsRegular() && !info.IsDir() {
		return fmt.Sprintf("(write error: %s is not a regular file)", path)
	}
	if dir := filepath.Dir(path); dir != "." {
		if err := os.MkdirAll(dir, 0o755); err != nil {
			return fmt.Sprintf("(mkdir error: %v)", err)
		}
	}
	if appendMode {
		f, err := os.OpenFile(path, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o644)
		if err != nil {
			return fmt.Sprintf("(write error: %v)", err)
		}
		defer f.Close()